Based on different types of communication paths from a source to a sink in a radio communication system, the structure of the radio communication system may include:
a network that allows direct communication between the source and the sink, e.g., a cellular network;
a network that requires a Relay Station (RS) to forward data between the source and the sink in the communication, e.g., a relay network, Ad hoc network, multi-hop network and mesh network in the field of communication technology, and such networks are referred to as forwarding networks.
If a branch of the cellular network includes an RS, e.g., a repeater, between a source and a sink, the branch is a portion of a forwarding network. The branch is a path between the source and the sink.
In a forwarding network, an RS needs to occupy radio resources different with the radio resources occupied by the source and sink to forward data. Therefore, an appropriate data transmission mode should be set for the forwarding network to allocate radio resources properly so as to prevent system interference from increasing. In addition, when a node in the forwarding network moves, the data transmission mode should be able to be adapted to the changed network structure.
In the forwarding network, a source node is defined as a node with a hop number of 0; and along the direction from the source node to a sink node, the hop number of every newly added node increases by 1, and the hop number of the branch also increases by 1, the link between the node with a hop number of N−1 and the node with a hop number of N is the Nth hop link. Similarly, the cellular network may also be regarded as a forwarding network with a hop number of 1.
The Fixed transmission mode is a transmission mode for the forwarding network of the related art. Specifically, the transmission mode is determined according to the maximum hop number in the forwarding network, that is, the time in a frame is divided into time slots, the number of which equals to the maximum hop number in the forwarding network, and the time slots are respectively assigned to links with different hop numbers; then, in a downlink, the source node (0th hop) transmits data to the nearest 1st hop RS or Subscriber Station (SS), which, upon the receipt of the data, forwards the data to the 2nd hop RS or SS, and the rest process is performed in the same way, until the data reaches the sink node. The transmission process on the uplink is opposite to the process on the downlink.
The fixed transmission mode is easy to control and, since a complete transmission process, including the data transmission from the source node to the sink node and the response from the sink node to the source node, may be finished in one frame, the fixed transmission mode limits the traffic delay in the time of one frame.
However, the inventor finds that the disadvantages of the fixed transmission mode include: low spectrum effectiveness, because only one entity with a certain hop number transmits data in the whole forwarding network at a time so that the space resources of the forwarding network cannot be fully utilized; and incapable of adjusting the data transmission scheme when the maximum hop number of the forwarding network changes, because the frame structure of the data limits the maximum hop number of the forwarding network.
The Dynamic transmission mode is another transmission mode for the forwarding network of the related art. The dynamic transmission mode does not limit the hop number of the forwarding network and transmits the data of one hop in one frame. In the dynamic transmission mode, the time and spectrum resources may be reused, therefore the space resources of the forwarding network may be fully utilized and the spectrum effectiveness is high; in addition, the dynamic transmission mode is able to be adapted to the changed network structure and thus guarantees the free expansion of the network.
However, the inventor finds that the disadvantage of the dynamic transmission mode includes a long traffic delay in the forwarding network.